Backup systems for computers are well known. Backup systems provide for the redundant storage of data, so that a computer can be restored to a previous state after an event that results in the loss of data on the computer. As those skilled in the art will appreciate, data stored on a computer can be very valuable and the loss of data can result in severe economic hardship.
Banks, stock brokerages, and other companies commonly store large amounts of data on computers. This data is vital to the day-to-day operations of such businesses. For example, it is easy to appreciate that a bank's account records, which are commonly stored in a computer, are necessary in order to facilitate the regular business transactions of the bank.
Events such as fires, earthquakes, thefts, and hard disk failures may result in the loss of valuable computer data. If the only copy of a company's data is stored on the affected computer, then the loss may be permanent and may have catastrophic consequences.
However, if the data was previously backed up, then the data may be restored, so that the routine operations of the business may continue with a minimum of disruption. Thus, the backing up of data stored on computers is considered necessary and has generally become routine.
Backup systems typically comprise a storage device and software, which drives the storage device. The software is configured so as to copy all or a portion of the data from a computer to media of the storage device. Various different types of storage devices are in widespread use. Compact disc (CD) and digital virtual device (DVD or DVD-ROM) backup systems are common on computers with smaller data storage requirements. Tape storage devices are used on computers with large data storage requirements.
The networking of computers had, for a time, simplified the backup process by providing a central data storage location for multiple computers. That is, several client computers were commonly connected to a single server and all of the data used by the client computers was stored in a central location by the server. Thus, only the single server needed to be backed up in order to adequately safeguard the data used by all of the client computers.
However, as the data needs of client computers increased over time, the ability to transfer the required data between the client and host eventually became bottlenecked by the limited bandwidth of the network. Since the data storage capacity of the client computers continued to increase as hard disk capacities increased and hard disk costs decreased, it eventually became more practical to store the large amounts of data required by client computers at the client computers themselves, rather than at the servers where bandwidth restrictions would limit the client computer's access to the data. Thus, we are once again faced with having to backup multiple client computers.
Although sometimes the client computers may be able to backup onto CD or DVD media, many times the capacity of such media is insufficient. Further, the backup process cannot be as fully automated when CD or DVD media are utilized, since more frequent media changes are required as compared to tape backup. When the backup process is not fully automated, then backups may not be performed as frequently as desired and the risk of loss of data undesirably increases.
Hard disk storage devices are also used for backups. However, hard disks are comparatively expensive on a per gigabyte basis, are prone to failure, and have limited capacity.
Contemporary networks typically have tape storage devices so that the client computers can backup thereto in an automated and efficient manner. Larger networks may have multiple tape storage devices, as well as CD, DVD and/or hard disk storage devices. For example, one tape storage device may be located near the server or servers, while one or more tape, CD, DVD, or hard disk storage devices may be located near individual client computers.
Thus, in a contemporary network, data may sometimes be backed up on any selected one of a plurality of different storage devices at a plurality of different locations. Typically, the storage device at each location was initially placed there for a dedicated backup function. That is, each storage device was purchase and installed so as to service a particular computer or group of computer.
However, since the storage devices and the computers that need to be backed up are frequently part of the same network, the opportunity to select a particular storage device arises.
The ability to select which one of a plurality of different storage devices is to be used for a given backup task has some advantages. For example, if the capacity of the usual storage device will be exceeded for the next backup, then a different storage device having a higher available capacity may be selected.
An operator, such as a network administrator, must typically specify where the data for a particular computer is to be backed up. Frequently, the administrator specifies that the data for a particular computer is to be backed up on a nearby storage device, which has sufficient capacity. However, this may not be the best choice for a variety of different reasons. Further, this choice may not always be available when desired. For example, the desired storage device may be out of service at the moment.
The nearest storage device to the computer being backed up may not be the best choice because a single event may destroy both the data stored on the computer being backed up and data stored on the storage device. For example, a fire that destroys the building within which both the computer being backed up and the backup storage device are located will have prevented restoring the data. Thus, it is generally desirable to backup data on a computer that is located remotely with respect to the computer being backed up.
However, in some instances it may be desirable to backup a computer to a storage device that is located near the computer. For example, the network administrator may intend to immediately remove the media from the storage device and move it to a remote location for safekeeping.
Further, an attempt to backup data on a remote storage device may result in problems due to bandwidth limitations of the network. In some instances, sufficient bandwidth may exist so as to facilitate backup within a reasonable amount of time and without undesirably interfering with the network usage of other computers. In other instances, the use of a remote storage device may result in the backup process taking an undesirably long time and/or interfering with routine network utilization.
Thus, in some instances it may again be more desirable to use a storage device that is located near the computer being backed up and in other instances it may be more desirable to use a computer located remotely with respect to the computer being backed up.
Additionally, it is generally desirable to always backup a particular computer with the same storage device. In this manner, the network administrator always knows where the backups for a particular computer are located when they are needed. Also, if all of the backups for a particular computer are on the same storage device, then the network administrator needs to restore data only from that particular storage device (rather than from a plurality of different storage devices), thus simplifying the restoration process.
Although such contemporary backup systems have proven generally suitable for their intended purposes, they possess inherent deficiencies, which detract from their overall effectiveness and desirability. For example, a network administrator must typically determine which of a plurality of different storage devices should be used to perform a given backup. The network administrator may lack sufficient information needed to make an optimal decision. Further, the network administrator may have other duties and may thus consider the performance of data backups a nuisance.
As such, although the prior art has recognized, to a limited extent, the. problem of automating backups, the proposed solutions have, to date, been ineffective in providing a satisfactory remedy. Therefore, it is desirable to provide a backup system that automatically performs storage device selection in a manner that tends to optimize predetermined criteria.